How to monitor the foliage Evapotranspiration with arduino

[pierrot10]

Good day all,

I actually monitor the amount of water of some appale tree in a orchard with 3 Watermark sensors.
In order to have better result on how and when to watering the apple orchard, I would like to monitor the evapotranspiration of the crop or better, the foliage.

I once saw an evapotranspiration sensor but I can not find anymore.

Someone would have a recommandation to monitor the evapotranspiration of the plants, with Arduino? (sensor, how to?...) Is there sensore for that purpose?

Many thank for any tips and hints to start my task

[wallyllama]

Wikipedia has some clues. A scintillometer which measures fluctuations in refractive index of air, just add math.

Satellite imagery +math

Lysimeter - measure the weight of a column of soil, im guessing dry soil is lighter.

All of thoose sound like lots of money.

A scintillometer seems doable as diy. For an area like a tree, I'd start with a laser diode ( i dont know which frequency, but as a complete guess id try infrared, possibly red, and stay away from green and blue), the other end would be either a phototransistor or a photocell. A low noise (probably high gain) amplifier and a quality anolog to digital converter (maybe a 24 bit sound card, probably a pi zero attached not an arduine or esp)

This is all very speculative(pun intended) on my part, it could be completely wrong, i am guessing based on the few words in wikipedia.

Wikipedia

[wallyllama]

Hmmm. Looking up scintillometers, I see they are advertised as "large aperture", so you may need an array of photo[diodes,cells], which adds a lot of complexity, matching, summing etc,but maybe you could get away with a condenser lens.